1. Field of the Invention
The present invention relates to a position sensor, and, more particularly, to a rotary position sensor.
2. Description of the Related Art
Electronic devices are an increasing part of everyday life and they are presently integrated in a large number of products, including products traditionally thought of as mechanical in nature, such as automobiles. To bridge the gap between mechanical movement and electronic control, it is necessary to successfully integrate electronic and mechanical components. This gap is normally bridged by using devices such as sensors and actuators.
Position sensors are used to electronically monitor the position or movement of a mechanical component. The position sensor produces data that may be expressed as an electrical signal that varies as the position of the mechanical component changes. Position sensors are an important part of innumerable products, providing the opportunity for intelligent control of a mechanical device.
Various contact-type sensors are known. For example, potentiometers are used, which detect a change in electrical signal due to a physical change in position of a wiping contact on an electrical resistive element. Rotational position movement can be detected by coupling a shaft of a potentiometer to the shaft of a rotating mechanical component. Linear movement can be detected either using a linear potentiometer or a rotating potentiometer that is coupled to a linear-moving component using pulleys and a string or a belt to translate a linear motion to rotational motion. A problem with this type of sensor is the physical wearing of the contacting parts. The wiping contact and the resistive element can cause a drift in the electrical signal, which induces errors and may lead to ultimate failure of the device.
Magnetic velocity sensors are generally a non-contact type of sensor and consist of a magnetic field sensing device, which is usually stationary, and a magnet is attached to a moving component. As the magnet approaches the sensing device, the magnetic field of the magnet is detected and the sensing device generates an electrical signal that is then used for counting, displaying, recording and/or control purposes.
What is needed in the art is a position sensor capable of sensing the position of a multi-turn device.